1: I don't know if the lib work with ATmega324 and I don't know Arduinos with that processor. The typical processor is ATmega328.
It is sold here. http://www.e-gizmo.com/KIT/gizduino+%20164,324,644.html
2: Have you use level-shifters or does your Arduino run with 3.3V only? If the Arduino is 5V you need level-shifters or you could broke your SD card. The simplest way to build a level-shifter is using two resistors for every of the four input pins at the SD card. A description can be found in file SimpleSDAudio.h.
It has 3.3V. No need for level shifters.
3: You have to power the SD card as well - connect GND to pin 3 and 6 of SD-card and connect pin 4 to the 3.3V output of the Arduino.
Did that already.
4: If there is no sound try the example BareMinimumWithDebug first and look at the output from the serial port. This can give you an indication if your wiring is still wrong or if there is something wrong with the filesystem on card or the file. You can post this output here in the forum to get more help.
It failed the first test. And I am not certain where to connect the cs pin. Digging the datasheet of 328 and 324 does not help. I am having a hard time understanding both.